The main components of all fats are fatty acids that may be saturated, monounsaturated or polyunsaturated. Fats contain a high proportion of saturated fatty acids that are solid at room temperature. They are known as saturated fat and usually are of animal origin such as lard, tallow and butter. Most vegetable fats are rich in polyunsaturated fat or monounsaturated fats except palm and coconut, which are highly saturated.
Saturated and monounsaturated fats are not necessary in the diet, as occurs in the human body.
Two polyunsaturated fatty acids (PGA) that the body cannot produce: linoleic acid and alpha linolenic acid are necessary. We need to obtain them from the diet and are known as essential fatty acids. Once in the body, they can be converted to other AGP, such as arachidonic acid, eicosapentaenoic acid (EPA) and the docosahexanoic acid (DHA).
In the body, the AGP is important to maintain the membranes of all cells to produce prostaglandins that regulate many body processes, for example, inflammation and blood clotting. Also, fats in the diet are necessary for fat soluble vitamins in foods (A, D, E and K) could be absorbed and to regulate cholesterol metabolism.
Polyunsaturated fatty acids: food sources
Here are the food sources of the two major polyunsaturated fatty acids (linoleic and alpha linolenic acid).
Linoleic acid (Omega 6 family):
- Vegetables, fruits, nuts, grains and seeds.
- Good oils are safflower, sunflower, corn, soybeans, squash, and wheat germ.
Alpha linolenic acid (Omega 3 family):
(Note: the fish is not the only source of omega 3. The linseed oil contains twice as much as fish oil!).
- Flaxseed oil (linseed) mustard, pumpkin seeds, soybean, walnut and rapeseed.
- Green leafy vegetables and cereals.
- A good source is flax, flaxseed, canola and soybean oil.
EPA and DHA
In the body, alpha-linolenic acid is converted into EPA (eicosapentaenoic acid), which is normally found in marine oils and DHA (docosahexanoic acid) that is normally found in marine fish oils. There are many factors that affect the conversion rate and one of them seems to be an abundant intake of linoleic acid, typical of vegan diets, which can reduce the body's ability to convert alpha-linolenic acid into DHA. To obtain a better balance of AGP in the body tissues, vegans can consume less sunflower, safflower and corn oils containing alpha linolenic acid, for example, rapeseed oil or soybean oils and walnut oils. In this way, produce more tissue DHA.
Many expert committees recommended that the general population should reduce fat consumption. Normally, only vegan diets met current indications, that fat should not be more than 35% of total energy intake in adults and children.
Saturated fats contribute to ensuring high levels of blood cholesterol, a risk factor for atherosclerosis and heart disease, while polyunsaturated fats (AGP) have the opposite effect. Vegan diets, which contain no meat or dairy fats, are low in saturated fatty acids and high in beneficial AGP. Vegans consume significantly more linoleic acid, an essential AGP.
Eicosapentaenoic acid (EPA) and the docosahexanoic acid (DHA), are two AGP not essential in vegan diets. The human body can convert alpha-linolenic acid into EPA and DHA, but even so, some of the vegan body tissues contain less DHA and EPA than those of other groups of diets. The consequences of this difference, if any, are unknown.
Similarly, the breast milk of vegan, vegetarian and omnivorous contain different proportions of some polyunsaturated acids levels, and these differences are reflected in some tissues of infants. Not yet know the effect, if any, that these variations may have on the growth and development of babies.
For more information on essential fatty acids and the vegan diet in general see Vegan Nutrition by Gill Langley. This book is the most comprehensive report available on scientific research on vegan diets. It is ideal for vegans interested in becoming health professionals. It contains points, user-friendly tables and chapter summaries.